1. Field of Invention
The present invention relates to medical devices. More particularly, the invention relates to a medical device for embolic protection.
2. Background
With the continuing advance of medical techniques, interventional procedures are more commonly being used to actively treat stenosis, occlusions, lesions, or other defects within a patient's blood vessels. Often the treated regions are in the coronary, carotid, renal, peripheral, cerebral and other blood vessels. For example, atherectomy or thrombectomy devices can be used to remove atheroma or thrombus. Another procedure for treating an occluded or stenosed blood vessel is angioplasty. During angioplasty, an inflatable balloon is introduced into the occluded region. The balloon is inflated, pushing against the plaque or other material of the stenosed region and increasing the intralumenal diameter of the vessel. As the balloon presses against the material, portions of the material may inadvertently break free from the plaque deposit. These emboli may flow downstream where they may block more distal and smaller blood vessel restricting blood flow to a vital organ, such as the brain. Consequences of embolization include stroke, diminished renal function, and impairment of peripheral circulation possibly leading to pain and amputation.
To prevent the risk of damage from emboli, various filtering devices have been proposed. Such devices typically have elements that form legs or a mesh that would capture embolic material, but allow blood cells to flow between the elements. Capturing the emboli in the filter device prevents the material from being lodged downstream in a smaller blood vessel. The filter may then be removed along with the embolic material after the procedure has been performed and the risk from emboli has decreased.
Many challenges exist with filtering devices. Often it is desirable to deploy filter devices, from the proximal side of a stenosis. Therefore, the profile of the filtering device should be significantly smaller than the opening in the stenosed vessel. If the profile of the filtering device is not significantly smaller than the opening, there is an increased risk of dislodging emboli during insertion of the device. Further, if the filter portion is not held against the inside of the vessel wall, there is a risk that embolic material may pass between the filter and the vessel wall. In addition, if the filtering device becomes filled with particles blood flow through the filtering device may be compromised.
In view of the above, it is apparent that there exists a need for an improved medical device for embolic protection.